Apparatus and method of making plastic binders



Feb. 24, 1942. I BARRETT 2,273,824

APPARATUS AND METHOD OF MAKING PLASTIC BINDERS Filed Dec. 19, 1939 QSheets-Sheet l H. G. BARRETT Feb. 24, 1942.

APPARATUS AND METHOD OF MAKING PLASTIC BINDERS a 4 Sheets-Sheet 2 Filed Dec. 19, 1939 Feb. 24, 1942. H. G. BARRETT APPARATUS AND METHOD OF MAKING PLASTIC BIND ERS Filed Dec. 19, 1959' 4 Sheets-Sheet I5 #4 010 G. E/JPRET-T Patented Feb. 24.1942 I.

' UNITED STATES PATENT OFFICE APPARATUS AND METHOD or 'MAKING PLASTICBINDERS.

" Harold G. Barrett,- Chicago, 111., assignor to Plastic Binding Corporation, Chicago, 11]., a corporation of Delaware Application December 19, 1939, Serial No. 310,081 I I 19 Claims.

This invention relates to apparatus for and method of forming binders and applying them to stacks of sheets and the like, and is particularly adapted, though not limited in its use, for

' forming binders to bind together sheets or leaflets, such as books, note books, magazines,

pamphlets and the like. The binder formed by the machine of the present invention is one such as is disclosed in the patent to Douvry, No. 1,970,285, granted August 14, 1934, and is in the present instance made of Celluloid, Pyroxylin, or

. any other suitable thermo-plastic material.

The material for forming the binders is first stamped, or cut out, to form a. continuous back portion from which a plurality of parallel fingers extend. The material used is suchthat it becomes plastic when heated, and may be formed to the desired shape, which shape is retained when the material cools. One of the principal objects of thepresent invention has to do with the provision of a novel method of and machine for curling fingers of the blank material upon themselves to form 'a'plastlc tubular binder of predetermined diameter.

The invention further consists in simultane ously shaping and applying the binder by insert-.

ing portions of the binder through aligned apertures in a stack of pages to be bound, and form: ing the binder to its requisite shape.

It is a still further object of the present 'invention to provide a machine of the character above described with means for directing and guiding portions of the binder through the apertures or aligned perforations of the stack of pages to be l tionedcharacter, with a magazine or the like for holding the blanks that are to be curled into binders and with means for automatically feeding the blanks, one at a time, to the curling portion of the machine.

It is a still further object of the present invention to provide a machine for forming bindersof the above character, which machine is of. a

simple, durable and compact construction and is effective and eflicient in operation.

While the present invention is particularly useful for forming binders of thermo-plasticmaterial, it is also applicable for forming binders of different materials, such as, for instance, of thin spring steel or the like, of the same shape as the thermo-plastic stock here illustrated. In dealing with spring steel binders the heating arrangement need not be used;

The attainment of the above and further objects ofthe present invention will be apparent from the following specification taken in conjunction with'the accompanying drawings forming a part thereof. I y

In the drawings:

Figure 1 is a vertical sectional view through a machine embodying the principles of the present invention;

' Figure 2 is a sectional view taken along the line 2-2 of Figure 1 and looking in the direction of the arrows;

Figure 3 is a horizontal view taken along the.

line 33 of Figure 1 and looking in the direction of the arrows;

Figure 4 is a sectional view taken along the line 4-4 of Figure l and looking in the direction of the arrows;

" Figure 5 is a fragmentary perspective view of a mandrel adapted for use in the machine of i e 1; V

Figure 6. is a fragmentary perspective view of a saddle for holding the mandrel of Figure 5;

Figure 7 is a fragmentary sectional view of 'oneend of the mandrel showing the samevin position in the saddle;

Figure "7A is a fragmentary perspective view of one end of the member for guiding and forming the binder strips;

Figure 8 is a vertical sectional view, on an enlarged scale, of a part of the machine of'Figure 1, showing the binder forming members when the machine is. open to receive a stack of pages to be bound; and r I Figure 9 is a view similar to Figure 8 and showing the corresponding apparatus in its closed or operated position.

Throughout-the drawings like reference numerals refer to like parts. Referring now more particularly to the drawings, l5 designates side members of the machine supporting frame, the side members being connected together by a cross member it that forms the back of a hopper or magazine H. A platform I8 is-secured to the upper ends of the side mem- I bers I5 in any desired manner, as by fastening screws l9, and constitutes a support for a stack of pages to be bound.

-At their back edges, the side members l5 of the supporting frame are provided with vertically extending outwardly directed flanges 20. A back plate 2| rests against the flanges 20 and extends from the bottom l6 of the hopper structure to a point slightly above the platform I8. The back plate 2| may be removably secured in position in any desired manner, as by fastening screws or bolts 22 passing through the flanges 20 (Fig. 4) and threaded into the plate 2| so that the fastening bolts or screws 22 are readily accessible for I the removal of the plate 2|.

The platform l8 terminates slightly in front of the back plate 2| to provide an opening 23 (Figs. 4 and 9) between the back plate 2| and ,the platform l8, through which opening the binder forming members are to be fed, one at a time, in a manner to be hereinafter set forth.

Within the magazine I1 is a front plate or pusher member 24 which is adapted to engage the binder forming stock 25 and force it towards the back plate 2| to a position such that the respective combs of the stock to be curled will be successively brought beneath the opening 23 to be successively ejected from themagazine.

v The pusher member 24 is preferably provided with depending-lugs of projections 25, which are preferably of a T-shaped formation, although and the ejector plate 35 are being raised. This energy is employed to return the slide 34 and the ejector plate 35 to their lowered or normal position to permit another binder forming blank to be moved into place for ejection upon the next upper movement of the ejector plate 35. The shaft 39 may be rotated in any desired manner, as by a rope or cable 43 (Fig. 1) which passes over a pulley M keyed to the shaft 39. One end of the cable 531s anchored to the Pulley M at 55, and the other end of the cable may be connected to any suitable operating mechanism, such as a foot treadle, so that upon manual exertion of a downward pull on the cable 93 the pulley is rotated in one direction. The energy stored in the spring 59 during such operation serves to return the pulley M to its initial position upon release of the pulley on the cable 93.

The platform I8 acts as a work table or support for the stack of sheets 55 constituting the magazine, book, or the like to be bound. The

rear end of the table it may be formed of any desired material, such as hardened steel, and is rabbeted to receive a saddle member M (Fig. 6). Saddles 58 are formed at opposite ends of the saddle member M. One of the saddles of the member All. may be provided with apin 59 therein. The rear edge of the saddle member ll forms an upright wall 50 which is adjacent to but spaced any other preferred shape may be used, so that ,the projections fit into and move within correspondingly shaped grooves 28 (Fig. 2) in the cross member it. Any number of these lugs 25 may be provided.

Connected to each lug, as at 29, is a flexible cable 29. Each cable passes over a pulley 30 keyed to a shaft 8| journalled in suitable bearings 32 in the supporting frame structure. The pulleys are located close to the rear of the magazine and project through openings 33 in the bottom member I6, as may be seen from Figure 1. The cables 29 depend from the pulleys 30 and have suitable weights secured to their lower ends which tend to move the pusher member 24 rearwardly to force the binders 25 rearwardly towards the plate 2| so that the binders may be successively ejected.

A slide 34 has an ejector plate or plunger 35 secured thereto, as by suitable fastening screws 35. The ejector plate is of a thickness only slightly less than the width of the opening 23 through which the binder members 25 are fed.

The opening 23 extends beyond the side walls of the magazine H, as may be seen at 23a in Figure 4, so that the edges of the ejector plate 35 are guided in the openings 23a during the vertical movement of the ejector plate, so that the edges or openings 23a serve as guides for holding the ejector plate in proper position.

Racks 31 are secured to the slide 24 adjacent the ends "thereof in anydesired manner and mesh with spur gear wheels 38 that are keyed to a shaft 39 journalled in suitable bearings 40a in the supporting frame. A coiled spring 40 encompasses the shaft 29, preferably between the gears 38. One end of the spring is secured to the shaft, or to a part that is keyed to the shaft,

Thus when the shaft is rotated in one direction energy is stored in the spring 40 as the slide 34 from the rear plate 2| to form a continuity of the slot or opening 23, as may be seen from Figure 8. The upper extremity 5| of the rear edge of the saddle member terminates preferably a short distance above the upper surface of the platform Hi. The upper face of the rear portion of the saddle member 51 is cut away to form a concave seat 52.

Pivotally mounted, as at 53, is a head member 54 having a concave portion in its lower face cooperating with the concave portion 52 in the member 41. The head member 5a is adapted to be moved about-the pivot 53 by an operating lever or handle 56 bifurcated to form side arms 57. The arms 51 are pivotally connected to the head member 54 by pivot pins 58. Each of the arms 51 may be formed into a hook-shaped portion 59 adapted to engage, respectively, under lugs or pins on the side member l5 of the supporting frame. A cross bar 6| connects the arms 51 of the lever 55 forward of the head 54 and is so positioned that when .the lever 56 is moved about its pivot 58 in one direction it will engage the front of the head 54 to hold the head down and also to assist in moving the head 54 about its pivot 53 in one direction. When the lever 56 is moved in the opposite direction, namely, counter-clockwise, to disengage the hookshaped member 59 from the lug 60, the cross member 52of the bifurcation will engage against a face or projection 63 on the head 54 to swing the head upwardly about its pivot 53. The stop 64 is provided on the head 54 to engage a portion ofthe supporting frame and thereby limit the upper movement of the head 54 and at the same time 'serve as a means for assisting and holding the head elevated.

Secured to the head 54 and seated within the v thereinto.

screws as. One edge of the member as terminates preferably substantially flush with the lower face of-the head 54. The fingers 65a project. below the lower face of the head 54 into the concaveseat 52 in the member 41 at the rear edge of the platform 18. The extremities of the fingers 65a are preferably beveled, as indicated at 58, and the forward edge of the concave seat 52 is preferably inclined orbeveled, as indicated at 69, to facilitate entrance of the fingers 650: When the head 54 is lowered to the position'illustrated in Figure 9 the face 10 there- The combs or stock from which the binders are to be curled, designated generally by the reference numeral 25 in Figure 1, are stackedone 6 of will rest against'the upper face of the rear I plate 2i'so that the concave surface '55 together with the concave surface 52 forms a chamber circular in cross section. One or more plungers II are carried by the head 51 and located in proximity to the face of the depending portions 68 of thevfingers 65a for holding the sheets of the stack of pages to be bound immovable and in compressed condition. Each plunger II is pro- 'vided with a spring 12 which tends normally to project the plunger ll downwardly, the spring being normally under compression. The mandrel 13 is provided-with a supporting shoulder 14 with a slot'18 opening through the lower face thereof and into which slot projects the pin 49 of the saddle 48 to hold the mandrel against turning in the saddle. The slot 'IBalso opens through the'e'nd of ,the mandrel so thatwhen the mandrel" is in position in 'the. saddle it may be removed therefrom by sliding the same endwise.

The stock for making the binders by themachine of the present invention is thermo-plastic, as previously 'pointed out. The machine of the present invention-is provided with means for applying heat to the stock to be formed into binders so that the stock becomes pliable and may be formed to its requisite shape and will retain that shape upon cooling. The end member 2| is provided with a-chamber 19 in which is located an electric heating element 88 whereby the plate will be heated'sufliciently to impartthe necessary initial plasticity or softness to thestock .to be formed. A second heating element 8i is arranged in'the head 54 so as to heat the head 54 and thereby apply heat to the stock as the same is being curled or shaped through the head. The

electric heating elements are supplied with energy from any suitable source, and the tempera.- ture may be controlled in any suitable manner. The heating elements may be rendered active or inactive at will, in accordance with the nature of which bears against theplate 2|. pages 46 to be bound, having'aligned spaced perforations of a spacing corresponding to the spacagainst the other within the hopper or magazine lland are backed by the'follower 24, the foremost comb resting against the follower 24 and the rear-most comb restingag'ainst the rear plate 2i. The mandrel 13 is placed in position in the saddles 48 for the operation of curling the rearmost comb within the hopper, namely, that comb A stack of ing of the fingers 83 of the comb and of a size such as to permit the fingers of the comb to pass therethrough readily, is then placed upon the platform [8 with the back of the stack of pages bearing against the portion -16 of the mandrel and with the edge of the sheets bearing against any suitable stop so that the perforations of the sheets are in alignment with the fingers of the binder as the stock is being curled.

The head 54 is then lowered, as by the handle 56, and the hook-shaped ends of the arms 51 are engaged under the lugs to lock the parts in the position illustrated in Figures 1 and 9. As the fingers 650. at the forward edge of the member were lowered they entered .the registering openings or perforations 84 in the sheets 46 to be bound, thus positively aligning the sheets so that upon the subsequent curling of the binder thev fingers 83 of the stock will be positively brought into the openings.

engage and press upon the sheets 46 and exerta The plungers 1| now spring pressure 'thereagainst immediately adjacent the mandrel. The pressure of "the plunger 1|, exerted by the spring 12, issufiicient to hold the ends of the stack of 'sheets or magazine in position.

The cable 43 is then pulled downwardly in any desired manner, as by a foot treadle, to rotate the pulley 44 in a direction clockwise, as seen in Figure '1. The pulley 44 rotates the shaft 39 and thus rotates the two jspur gears 38 which, by engagement with the raclgs3'l, raise the racks and slides 34 which carry the plunger 35. The

plunger. 35 is thus raised to engage the lower edge of the rearmost binder 25 to force that binder upward through the opening 23 and against the inner face of the member 65. It is to be noted that at this time the rearmost comb which is v being forced upwardly has been in contact with the heated end plate 2| and is thus quite hot.

thematerial of which the binders are being,

formed.

The stock from which the binders are curled consists of fiat sheets of thermoplastic material cut to a comb shape and having a back portion 82 (see particularly Fig. 2) from which extend latverally spaced teeth 83 integral with the back portion. The combs are stamped or cut from sheets of suitable thermo-plastic material, suchv as Celluloid, pyroxylin, or the like, or preferably from a thermo-plastic material which is slow'burning,

non-explosive and does not become brittle, or crack after long periods of time. The material known as Vinolite is one such suitable material;

The head 54- is also hot so there is no chilling of the stock as it is being pushed upwardly. The fingers 83 of the comb 25 are thus being pushed upwardly between the hot tool steel die member 65 and the mandrel 13. Continued upward movement or ejection of the comb or stock 25 will cause the latter to be curved around the inner faceof the die 65 and the fingers 65a 'of the die. The fingers'83 of the stock are thus curled through the perforations 84in the stack of pages to be bound. Ultimately, the forward edges of the fingers 83 of the comb strike the 'the pulley in the opposite direction, thereby lowering the plunger. As the plunger drops betemperature.

low the bottom of the 'rearmost comb in the magazine or hopper thefollower 24 causes the stock 25 in the hopper to move back by the thickness of one comb so thatthe rearmost comb of the magazine is again in contact with the hot plate 2| to be heated thereby preparatory to the next curling operation.

After the binder has been shaped or formed through and by the stack of pages to be bound, the head 54 is raised by moving the handle 56 upwardly. The first such movement of the handle 56 causes the arms 51 to unlock the head from behind the lug 60. Continued movement of the handle 56 brings the handle against the stop 53 so that further movement of the handle causes the head 54 to swing counter-clockwise from the positionillustrated in Figure 1. The

"mandrel 13, if a mandrel is used, may then be withdrawn edgewise from the shaped binder, the slotted end 18 of the mandrel. permitting disengagement with the pin 49 in the saddle 48. The bound stack of pages or book d6 may then be removed from the table 58.

As previously stated, the material from which the combs or binder are made is ductile andwill retain its shape after it has formed and become set. It is within the purview of the present invention to use thin metal binders in lieu of plastic binders, if desired. If that is used then,

of course, the heating elements are not necessary.

The heating element 80 in the plate 2! preheats the supply of combs adjacent the comb that bears against the plate 2! so that when the comb which bears against the plate 2| is ejected, the next comb. has already been preheated, whereby only a small amount of additional heat is necessary to bring it to its requisite curling The machine is operated at such a temperature that each comb being curled is sufiiciently ductile or plastic to be formed to its requisite shape and yet is not soft, and is sufiiciently firm to retain that shape ,as it is forced through the die 65. When the head 54 is raised the heated curled binder then on the mandrel commences to cool so that after a few moments the binder has set sufficiently to permit removal of the arbor.

It is to be noted that the diameter of the chamber formed by the die 65, the fingers 65a andthe seat or recess 52 in the member 41 at the end of the platform or support I8 is such with relation to the length of the binder stock while in the fiat condition, that when the binder is forced into the chamber it will be coiled or shaped to such an extent that the free ends of the fingers v83, that is, the ends of the fingers remote from the back 82, will overlap the back 82 of the curled comb, as shown in Figure 9. As a result of this overlap it is not possible for the end sheets of the bound stack to become accidentally detached from the binder.

When combs or binder members of a smaller length than thoseshown in Figure 2 are to be used, one or more filler plates 85 (Fig. 2) may be placed in the magazine and likewise a stop 86 (Fig. 2) may be employed in connection with the platform I8, said filler plates and gauges being arranged on either or both sidesof the magazine l1 and platform 18 so that the stock to be curled is maintained in proper alignment with the stack of pages to be bound.

If desired, there may be provided a supplemental locking member 81 pivotally connected as at 88 (see particularly Fig. 1) at the forward While I have herein described a method of' operating the machine of the present invention to curl binder stock-and simultaneously insert it through the perforations in a stack of pages,

it is within the purview of the present invention to curl the stock in the absence of a stack of pages to be simultaneously bound by the stock.

This may be done by merely-omitting the stack of pages 46. The stock 25 is then curled to form binders of the type previously described herein, which binders may be sold as articles of manufacture to' be later inserted into stacks of pages having aligned perforations. The binder stock iis elastic and may be uncurled, within the limits of its elasticity, to receive a stack of pages and then be permitted to recurl under its own elasticity so that the fingers enter the aligned perforations in the stock. A suitable machine for effecting this binding operation is shown in the patent to C. B. Nelson and Isidore Spinner, No, 2,108,136, issued February 15, 1938. If the stock is to be curled without simultaneous insertion in a stack of pages, then the arbor or mandrel 13 need not have the cut away portion 15-16 but may be in the form of a completely cylindrical rod. Also, under such circumstances, it is not essential that the mandrel be locked against rotation. A turning of the mandrel under such circumstances is of no harm and may sometimes be actually beneficial. Therefore the slot l8 and pin t9 may be omitted.

In compliance with the requirements of the patent statutes I have here shown and described a preferredembodiment of my invention. It is, however, to be understood that the invention is not limited to the precise constructions here shown, the same being merely illustrative of the principles of the invention. What I consider new and desire to secure by Letters Patent is:

1. In an apparatus for applying binder strips to sheets which are provided with openings adjacent one edge, a mandrel, means removablysupporting the mandrel adjacent said edge of the sheets, means for holding the sheets, means for holding a stack of binding strips, means for feeding the foremost strip of the stack simultaneously about the mandrel and to the sheets, the remaining strips advancing progressively as the foremost into a loop about the mandrel, and means for directing the strips through the respective openings in the sheets as each of said strips is being formed into a loop, said mandrel .and loops being separable by relatively moving one with relation to the other in a direction transverse to the plane of the loop.

2. In an apparatus for applying a binder strip to sheets which are provided with openings adjacent one edge, a mandrel, means removably supporting the mandrel adjacent said edge of the sheets, means for gripping the sheets, a die movable into the openings in the sheets, means for feeding the strip about the mandrel and along the die into the sheets, means for shaping the strip into a loop about the mandrel. the said loop being closed with the ends of the strip overlapping for a considerable extent, and means for directing the strip through said openings in the sheets as said strip is being formed into a loop, said mandrel being removable from the loop in a direction transverse to the plane of the loop.

3. In a machine for applying binder strips to sheets .which have openings adjacent one edge,

. means for holding the sheets, means for holding a supply of binder strips, means for advancing the strip edgewise to the sheets, a mandrel, means for forming the strip into a loop about the mandrel and within the plane of the edges of the strip and with the ends of the loop overlapping for 'a considerable extent about a mandrel,.and means for directing the strip-through the said openings as the loop is being formed, the said mandrel and loops being removable and separable one with relation to the'other in a direction transverse to the plane of the loop.

, 4.'In a machine for applying a'binder strip to sheets which are provided with openings adjacent openings adjacent one edge, a shaping form embodying members separable for receiving said edge of the sheets between them,'means for maintaining them against separation, and means engaging the back of a comb-shaped binding strip and forcing it edgewise teeth foremost into the form, the said form operating to shape the strip into a.loop, a portion oi one of the members of 8. In a machine for applyinga binder strip to sheets which are provided with openings adjacent one edge, a shapingform embodying members separable for receiving said edge of the sheets between them, means for maintaining them against separation, and means engaging one end of a binding strip, and pushing it forward for from one edge thereof, said form operating to feeding the strip edgewise into the form,-said strip being in the form of a comb having a body portion and laterally spaced teeth extending shape the teeth into loops, as the strip is fed thereinto, portions of one of the members of the form serving to direct the teeth of the strip through the respective openings in the sheets as the strip .is being shaped into a loop, the ends of the teeth overlapping the edge of the strip opposite to the edge on which the teeth are located.

9. In a machine for applying a binder strip to sheets which are provided with openings adjacent one edge, a shaping form embodying members separable for receiving said edge of the sheets between them, means for maintaining them against separation, and means engaging one end of a binding strip and pushing it forward for feeding the strip edgewise into the form, said strip being in the form of a comb having a body portion and laterally spaced teeth extending from one edge thereof, said form operating to shape the teeth into loops, as the strip is fed thereinto, portions of one of the members of the form serving to direct the teeth of the strip through the form serving to direct the strip through the openings in the sheets as the strip is being shaped into a loop, the ends of the loop overlapping for a considerable extent.

6. In a machine for applying 'a binder strip to sheets which. are provided with adjacent aligned openings adjacent one edge, a shaping form embodying members separable for receiving said edge of the sheets betweenthem, means for removably supporting a mandrel in the form, means for separating the members, means for maintaining the members against separation, and means engaging the back .of a' comb-shaped binding strip and forcing it edgewise teeth foremost into the form, the said form operating to shape the strip into a loop about the mandrel,

a portion of one of the members of the form serving to direct the strip through the openings in the sheet as the strip is being shaped into a loop, the said mandrel and loop being separable by removing one with relation to the other in a direction transverse to the plane of the loop.

7. In a machine for applying a binder strip to sheets which are provided withaligned openings adjacent one edge, a shaping form embodying members separable for receiving said edge of the sheets between them, means for maintainingthem against separation, and means engaging one end ,of a binding strip and pushing it forward for feeding the strip edgewise into the form, said strip being in the form of a comb having a body portion and laterally spaced teeth extending from one edge thereof, said form operating to shape the teeth into loops, as the strip is fed thereinto, portions of one of the members of the form serving to direct the teeth of the strip through the respective openings in the sheets-as the strip is being shaped into a loop.

- the respective openings in the sheets as the strip is being shaped into a loop.

..10. In a machine for applying a binder strip to sheets'which are provided with openings ad- }acent one edge,- a shaping form embodying member separable for receiving said edge of the sheets between them. means for maintaining the members against separation, a mandrel, means removably supporting the mandrel in the form, means for feeding a binding strip into the form,

said binding strip being in the fornr of a coinb having arbody and spaced fingers projecting from one edge of the body, said form operating to shape the strip into laterally spaced loop's, portions of one of the members of the form shaped to direct the loop through the respective openings in the sheets as the loops are being formed, said mandrel and loop being separable by moving one with respect to the other in a direction transverse to the plane of the loops.

.11. In, a machine for applying a binder to sheets which are provided with openings adjacent one edge, a shaping form embodying members separable for receiving said edge of the sheets between thennmeans for maintaining the members against separatioma mandrel, means removably supporting the-mandrel in the form,

means for feeding a binding strip into the form, said binding strip being inthe form of a comb having a body and spaced fingers projecting from one edge of the body, said form operating to shape the strip into laterally spaced loops, portionsiof one of the members of the form shaped to direct the loops through the respective openings in the sheets as the loops are being formed,

' said mandrel and loops being separable by moving with relation to the other in a direction transverse to the plane of the loops, and means formatting the form.

12. In a machine for forming a binder for sheets which are provided with openings adjacent one edge, a shaping form embodying separable members, means for maintaining the 11mm bers against separation, a mandrel, means removably supporting the mandrel in the form, means for feeding a comb-shaped binding strip into the form and curling the strip into loops, said binding strip being in the form of a comb having a body and spaced fingers projecting from one edge of the body said form having curved fingers for guiding and forming the fingers of the binder comb, said mandrel and loops being separable by moving with relation to the other in a direction transverse to the plane of the loops,

and means for heating the form.

13. A machine for shaping a strip of material having a back and a plurality of parallel fingers extending longitudinally thereof to form a binder having a plurality of rings extending at right angles to the back, said machine including die means for'imparting the requisite shape to the allel rings, said machine including means for advancing successive strips into feeding position, die means for forming the strip to its requisite shape, means for feeding each strip from its feeding position to the die means and forcing it about said die means, and means for heating each strip to a, temperature insufficient to cause it to' fuse but sufiicient to impart a permanent'set to the strip upon subsequent cooling-thereof,

15. A machine for curling thermo-plastic material for binding a stack of sheets, said machine comprising, a magazine for holding the stock to be curled, die means for curling the stock, means for ejecting stock from the magazine and forcing it about the die means, and means for heating each piece of stock ejected to a temperature insufflcient to cause it to lose itsshape but sufyficient to impart a permanent set to the stock upon cooling and release of the same from the die means.

16. The method of forming a piece of. thermo-plastic material having a back portion and a plurality of spaced parallel fingers extending from the back, 'which" comprises binder from a placing the piece with an edge thereof adjacent to and extending axially of a concave die, iorclng that edge of the piece into the die and sliding it circumferentially along the inside of the die, continuing the sliding movement until the foremost edge of the piece has moved through an angular distance exceeding 360 and applying to the piece a degree of heat insufficient to melt the same but sufficient to impart a permanent set to the material upon subsequent cooling thereof, and then permitting the material to cool.

17. The method of forming a binder from a piece of thermo-plastic material having a back portion and a plurality of spaced parallel fingers extending from the back, which comprises 'placing a mandrel on the inside of a concave die but spaced from'the die an amount sufiicient to permit movement of the material between the die and the mandrel, placing the piece with an edge thereof extending axially of the die and adjacent the space between the die and the mandrel, forcing said piece between the die and the mandrel so that the piece slides circumferentially along the inside of the 'die, continuing the sliding movement until the foremost edge of the'piece has moved through an angular distance exceed ing 360 and applying to the piece a degree of heat insufiiclent to melt the same but suflicient to impart a permanent set to the material upon subsequent cooling thereof, and then permitting the material to cool.

18. Binder curling apparatus for curling a comb-shaped thermoplastic strip into a plurality of loops joined by a common back portion, which comprises, an arbor, means for forcing a binder strip teeth foremost around said arbor and means for applying heat to said strip before it is forced around the arbor and as it is forced around the arbor.

19. The method of curling a strip of thermoplastic material which includes a plurality of adjacent parallel fingers joined by a common back, which comprises forcing the strip edgewise and fingers foremost between two dies to curl the fingers, continuing to push the back of the binder between the dies until the tips of the fingers have been moved through-an arc exceeding 860, and heating the strip to a temperature insuflicient to cause the strip to become tacky but sufficient to impart a permanent set-t0 the strip upon subsequent cooling thereof.

HAROLD G. BARRETT. 

